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We report the effects of composition on the performance, particularly the spectral response, of hybrid photovoltaic cells made of PbSe nanocrystal quantum dot (NQD)/poly-3(hexylthiophene) nanocomposites. Photocurrent measurements under monochromatic and white light illuminations were employed to characterize devices consisting of thin nanocomposite films with different NQD weight percentages. It was found that at different illumination wavelengths, the short-circuit current of the hybrid device responds diversely to the variation in the NQD loading. The finding is correlated to the optical and morphological properties of the nanocomposite films, which can be further linked to the absorption and carrier-transport properties. In addition, the observed power dependence of photocurrent on intensity has revealed the pseudomonomolecular recombination kinetics in the NQD-polymer nanocomposite, indicating that the efficiency of the hybrid photovoltaic cells can be enhanced by reducing the potential barriers formed by ligand molecules at the nanocrystal surfaces. [ABSTRACT FROM AUTHOR]

Low selectivity and the competing reaction of hydrogen evolution are two problems in photocatalytic CO2 reduction. Herein, we deposited highly crystalline metallic Cu nanoparticles onto TiO2 photocatalysts using a solvothermal method. They were found to convert CO2 into CO without any by-products. Importantly, hydrogen evolution can be suppressed after a reaction time of 1–2 h with a high generation rate and selectivity for CO production. [ABSTRACT FROM AUTHOR]

Hematite nanoarrays are important photoanode materials. However, they suffer from serious problems of charge transfer and surface states; in particular, the surface states hinder the increase in photocurrent. A previous strategy to suppress the surface state is the deposition of an Fe-free metal oxide overlayer. Herein, from the viewpoint of atomic bonding energy, it is found that the strength of bonding around Fe atoms in the hematite is the key to suppressing the surface states. By treating the surface of hematite with Se and NaBH 4 , the Fe 2 O 3 transforms to a double-layer nanostructure. In the outer layer, the Fe-O bonding is reinforced and the Fe-Se bonding is even stronger. Therefore, the surface states are inhibited and the increase in the photocurrent density becomes much faster. Besides, the treatment constructs a nanoscale p-n junction to promote the charge transfer. Improvements are achieved in onset potential (0.25 V shift) and in photocurrent density (5.8 times). This work pinpoints the key to suppressing the surface states and preparing a high-efficiency hematite nanoarray, and deepens our understanding of hematite photoanodes., (© 2020 Wiley-VCH GmbH.)

Electrochemical reduction of CO 2 was a widespread method for CO 2 conversion into valuable chemical fuel. C 2 H 4 is an important product from CO 2 reduction. However, conversion of CO 2 into the hydrocarbon C 2 H 4 faced large energy barriers. Herein, we, for the first time, achieve a high efficiency for electrochemical conversion of CO 2 to C 2 H 4 on a tin-modified CuO. By modifying with Sn, we obtained a related low onset potential of C 2 H 4 as positive as -0.8 V versus RHE and a high Faradaic efficiency of C 2 H 4 as high as 22% at -1.0 V ( vs RHE). According to density functional calculation, the Sn dopant mainly enriched the electron density of CuO, while it was electron-poor in the Sn dopants. The rate of CO 2 reduction can be enhanced on Cu nanosheets with higher electron density. We believed that this work would promote the development of two-dimensional catalysts for CO 2 conversion and deepen the understanding of doping on CO 2 reduction.

Low selectivity and the competing reaction of hydrogen evolution are two problems in photocatalytic CO2 reduction. Herein, we deposited highly crystalline metallic Cu nanoparticles onto TiO2 photocatalysts using a solvothermal method. They were found to convert CO2 into CO without any by-products. Importantly, hydrogen evolution can be suppressed after a reaction time of 1-2 h with a high generation rate and selectivity for CO production.